In recent years, a variety of optical disks have been proposed as disk-type information recording media removable from a recording/reproduction apparatus. Such recordable optical disks are proposed as media having a large storage capacity of several gigabytes and highly expected as media for recording an AV (Audio Visual) signal such as a video signal. Sources supplying digital AV signals to be recorded onto such a recordable optical disk include a CS digital satellite broadcasting station as well as a BS digital broadcasting station and, in the future, a proposed ground wave television broadcasting station.
In general, digital video signals supplied by these sources are subjected to picture compression normally adopting an MPEG (Moving Picture Experts Group)-2 technique. A recording-apparatus for recording the signals has a predetermined recording rate unique to the apparatus. When a digital video signal generated by a digital broadcasting station is recorded onto the conventional consumer image storing media, the digital video signal is decoded and then subjected to a band-limiting process if an analog recording technique is adopted. If a digital recording technique is adopted, on the other hand, the digital video signal is once decoded and then recoded at a recording rate peculiar to the recording apparatus by adoption of an encoding technique. Representatives of the digital recording technique include an MPEG1 video technique, an MPEG2 video technique and a DV (Digital Video) technique.
With such recording techniques, however, a supplied bit stream is decoded once before being subjected to band-limitation and recoding processes so that the picture quality deteriorates. If a transmission rate of an input digital signal completing picture compression does not exceed a recording rate of a recording/reproduction apparatus in an operation to record the digital picture, in order to minimize deteriorations in picture quality, it is possible to adopt a method to record the supplied video stream as it is without carrying out decoding and recoding processes on the input digital signal. If the transmission rate of the input digital signal exceeds the recording rate of a disk used as the recording medium, on the other hand, the digital signal needs td be decoded by the recording/reproduction apparatus and then recoded so that the transmission rate becomes lower than an upper limit of the recording rate before the signal is stored in the recording medium.
In the case of a digital-signal transmission adopting a variable rate technique whereby the digital signal is transmitted at a bit rate varying from time to time, a disk recording apparatus capable of recording data, which is temporarily stored in a buffer, in a burst operation is capable of utilizing the storage capacity of a disk used as an information recording medium efficiently in comparison with a tape recording technique with a fixed recording rate due to a fixed rotational speed of a rotary head.
As described above, in the future where the digital broadcasting is most popular, there will be a predicted demand for a recording/reproduction apparatus using a disk as a recording medium for storing a broadcasted signal as a digital signal without any processing including decoding and recoding processes in the same way as a data streamer.
As explained above, as the storage capacity of a recording medium increases, the recording medium can be used for storing a larger amount of data such as video and audio data of a program. Thus, a disk can be used for recording a number of programs. In consequence, the user needs to carry out operations such as editing to watch only desired programs selected from a number of programs recorded on the disk.
If an editing operation is carried out, however, it becomes difficult to properly manage data recorded on the disk and reproduced information.